title: Genetic evidence that Arabidopsis ALTERED ROOT ARCHITECTURE encodes a putative dehydrogenase involved in homoserine biosynthesis.
abstract: Genetic and molecular analysis of an Arabidopsis root development mutant identified a putative dehydrogenase gene involved in homoserine biosynthesis. In higher plants, homoserine (Hse) is derived from aspartate (Asp) and is an important intermediate for production of methionine (Met), threonine (Thr), and isoleucine (Ile). In Arabidopsis, six enzymes involved in the biosynthesis of Hse from Asp have been well characterized. It is not known, however, whether there exist other enzymes involved in this process. In this work, we characterized an Arabidopsis mutant, ara (altered root architecture), with a short primary root and an increased number of lateral roots. Genetic and molecular analysis indicated that the ARA gene encodes a protein with a D-isomer specific 2-hydroxyacid dehydrogenase domain. ARA is expressed in all plant organs and is localized in the cell periphery. The ara mutant phenotypes can be rescued by exogenously applied Hse, Met, Ile and 2-oxobutanoate. Based on the results presented here, we propose that the ARA protein may be a dehydrogenase involved in homoserine biosynthesis.
authors.affiliation: MOE Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Yuan
authors.forename: Dong
authors.initials: D
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D053898:Biosynthetic Pathways / Q000187:drug effects / Q000235:genetics; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics; D005816:Genetic Complementation Test; D006714:Homoserine / Q000096:biosynthesis* / Q000494:pharmacology; D007532:Isoleucine / Q000494:pharmacology; D008715:Methionine / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D007532:Isoleucine; D006714:Homoserine; D008715:Methionine; C000591891:ARA protein, Arabidopsis; D010088:Oxidoreductases